Investigation of using eggshell and calcium carbonate to improve biomass pellet energy efficiency

Abstract

Fossil fuel depletion and environmental concerns necessitate sustainable energy alternatives. Biomass, being abundant and carbon neutral, is a promising option. This study compares the effects of calcium carbonate (CaCO₃) and eggshell additions to biomass under identical pyrolysis and combustion conditions. Rice chaff and corncob were mixed with 2, 5, and 10% CaCO₃ or eggshells and pyrolyzed at 300 °C and 500 °C. Thermogravimetric analysis showed improved thermal stability, especially at higher mixing ratios. Elemental and proximate analyses revealed reduced carbon, hydrogen, and oxygen with increased ash, while FT-IR confirmed structural changes. A 2% mixing ratio best preserved combustion indices. Corncob-based samples at 300 °C exhibited excellent performance, with a calorific value of 28.20 MJ/kg and 66.58% energy yield. The findings indicate that eggshells, an accessible biowaste, perform comparably to commercial CaCO₃ in enhancing fuel properties. Their cost-free and eco-friendly nature makes them a viable biomass additive. Further research should explore industrial-scale applications and other calcium-based biowaste materials for optimisation.